1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Mutexes: blocking mutual exclusion locks
4 *
5 * started by Ingo Molnar:
6 *
7 * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
8 *
9 * This file contains the main data structure and API definitions.
10 */
11#ifndef __LINUX_MUTEX_H
12#define __LINUX_MUTEX_H
13
14#include <asm/current.h>
15#include <linux/list.h>
16#include <linux/spinlock_types.h>
17#include <linux/lockdep.h>
18#include <linux/atomic.h>
19#include <asm/processor.h>
20#include <linux/osq_lock.h>
21#include <linux/debug_locks.h>
22#include <linux/cleanup.h>
23#include <linux/mutex_types.h>
24
25#ifdef CONFIG_DEBUG_LOCK_ALLOC
26# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
27 , .dep_map = { \
28 .name = #lockname, \
29 .wait_type_inner = LD_WAIT_SLEEP, \
30 }
31#else
32# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
33#endif
34
35#ifdef CONFIG_DEBUG_MUTEXES
36
37# define __DEBUG_MUTEX_INITIALIZER(lockname) \
38 , .magic = &lockname
39
40extern void mutex_destroy(struct mutex *lock);
41
42#else
43
44# define __DEBUG_MUTEX_INITIALIZER(lockname)
45
46static inline void mutex_destroy(struct mutex *lock) {}
47
48#endif
49
50#ifndef CONFIG_PREEMPT_RT
51/**
52 * mutex_init - initialize the mutex
53 * @mutex: the mutex to be initialized
54 *
55 * Initialize the mutex to unlocked state.
56 *
57 * It is not allowed to initialize an already locked mutex.
58 */
59#define mutex_init(mutex) \
60do { \
61 static struct lock_class_key __key; \
62 \
63 __mutex_init((mutex), #mutex, &__key); \
64} while (0)
65
66#define __MUTEX_INITIALIZER(lockname) \
67 { .owner = ATOMIC_LONG_INIT(0) \
68 , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
69 , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \
70 __DEBUG_MUTEX_INITIALIZER(lockname) \
71 __DEP_MAP_MUTEX_INITIALIZER(lockname) }
72
73#define DEFINE_MUTEX(mutexname) \
74 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
75
76extern void __mutex_init(struct mutex *lock, const char *name,
77 struct lock_class_key *key);
78
79/**
80 * mutex_is_locked - is the mutex locked
81 * @lock: the mutex to be queried
82 *
83 * Returns true if the mutex is locked, false if unlocked.
84 */
85extern bool mutex_is_locked(struct mutex *lock);
86
87#else /* !CONFIG_PREEMPT_RT */
88/*
89 * Preempt-RT variant based on rtmutexes.
90 */
91
92#define __MUTEX_INITIALIZER(mutexname) \
93{ \
94 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \
95 __DEP_MAP_MUTEX_INITIALIZER(mutexname) \
96}
97
98#define DEFINE_MUTEX(mutexname) \
99 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
100
101extern void __mutex_rt_init(struct mutex *lock, const char *name,
102 struct lock_class_key *key);
103
104#define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex)
105
106#define __mutex_init(mutex, name, key) \
107do { \
108 rt_mutex_base_init(&(mutex)->rtmutex); \
109 __mutex_rt_init((mutex), name, key); \
110} while (0)
111
112#define mutex_init(mutex) \
113do { \
114 static struct lock_class_key __key; \
115 \
116 __mutex_init((mutex), #mutex, &__key); \
117} while (0)
118#endif /* CONFIG_PREEMPT_RT */
119
120/*
121 * See kernel/locking/mutex.c for detailed documentation of these APIs.
122 * Also see Documentation/locking/mutex-design.rst.
123 */
124#ifdef CONFIG_DEBUG_LOCK_ALLOC
125extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
126extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
127
128extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
129 unsigned int subclass);
130extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
131 unsigned int subclass);
132extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
133
134#define mutex_lock(lock) mutex_lock_nested(lock, 0)
135#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
136#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
137#define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
138
139#define mutex_lock_nest_lock(lock, nest_lock) \
140do { \
141 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
142 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
143} while (0)
144
145#else
146extern void mutex_lock(struct mutex *lock);
147extern int __must_check mutex_lock_interruptible(struct mutex *lock);
148extern int __must_check mutex_lock_killable(struct mutex *lock);
149extern void mutex_lock_io(struct mutex *lock);
150
151# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
152# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
153# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
154# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
155# define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)
156#endif
157
158/*
159 * NOTE: mutex_trylock() follows the spin_trylock() convention,
160 * not the down_trylock() convention!
161 *
162 * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
163 */
164extern int mutex_trylock(struct mutex *lock);
165extern void mutex_unlock(struct mutex *lock);
166
167extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
168
169DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T))
170DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T))
171DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0)
172
173#endif /* __LINUX_MUTEX_H */
174

source code of linux/include/linux/mutex.h